Implant delivery system with interlock

ABSTRACT

An implant delivery system is disclosed. The delivery system includes an elongated member having an implant mounting location. A self-expandable implant is mounted at the implant mounting location. The implant is held in a compressed orientation by a retractable sheath. An interlock structure prevents the implant from deploying prematurely as the sheath is retracted.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is a continuation-in-part of U.S. patentapplication Ser. No. 09/795,047 entitled Implant Delivery System withInterlock, that was filed on Feb. 26, 2001.

BACKGROUND OF THE INVENTION

[0002] 1. Field of Invention

[0003] This invention pertains to a system for delivering an implant toa site in a body lumen. More particularly, this invention pertains to adelivery system for a self-expandable implant such as a stent.

[0004] 2. Description of the Prior Art

[0005] Stents are widely used for supporting a lumen structure in apatient's body. For example, stents may be used to maintain patency of acoronary artery, other blood vessels or other body lumen.

[0006] Stents are commonly metal, tubular structures. Stents are passedthrough a body lumen in a collapsed state. At the point of anobstruction or other deployment site in the body lumen, the stent isexpanded to an expanded diameter to support the lumen at the deploymentsite.

[0007] In certain designs, stents are open-celled tubes that areexpanded by inflatable balloons at the deployment site. This type ofstent is often referred to as a “balloon expandable” stent. Other stentsare so-called “self-expanding” stents. Self-expanding stents do not useballoons to cause the expansion of the stent. An example of aself-expanding stent is a tube (e.g., a coil tube or an open-celledtube) made of an elastically deformable material (e.g., a superelasticmaterial such a nitinol). This type of stent is secured to a stentdelivery device under tension in a collapsed state. At the deploymentsite, the stent is released so that internal tension within the stentcauses the stent to self-expand to its enlarged diameter. Otherself-expanding stents are made of so-called shape-memory metals. Suchshape-memory stents experience a phase change at the elevatedtemperature of the human body. The phase change results in expansionfrom a collapsed state to an enlarged state.

[0008] A delivery technique for elastically deformable stents is tomount the collapsed stent on a distal end of a stent delivery system.Such a system would include an outer tubular member and an inner tubularmember. The inner and outer tubular members are axially slideablerelative to one another. The stent (in the collapsed state) is mountedsurrounding the inner tubular member at its distal end. The outertubular member (also called the outer sheath) surrounds the stent at thedistal end.

[0009] Prior to advancing the stent delivery system through the bodylumen, a guide wire is first passed through the body lumen to thedeployment site. The inner tube of the delivery system is hollowthroughout its length such that it can be advanced over the guide wireto the deployment site.

[0010] The combined structure (i.e., stent mounted on stent deliverysystem) is passed through the patient's lumen until the distal end ofthe delivery system arrives at the deployment site within the bodylumen. The deployment system may include radiopaque markers to permit aphysician to visualize positioning of the stent under fluoroscopy priorto deployment.

[0011] At the deployment site, the outer sheath is retracted to exposethe stent. The exposed stent is now free to self-expand within the bodylumen. Following expansion of the stent, the inner tube is free to passthrough the stent such that the delivery system can be removed throughthe body lumen leaving the stent in place at the deployment site.

[0012] In prior art devices, the stent may prematurely deploy as theouter tube is retracted. Namely, with the outer tube partiallyretracted, the exposed portion of the stent may expand resulting in theremainder of the stent being squeezed out of the outer tube. This canresult in the stent being propelled distally beyond a desired deploymentsite. Also, once the stent is partially unsheathed, it is sometimesdetermined that the stent placement needs to be adjusted. With existingsystems, this is difficult since the stent has a tendency to forceitself out of the sheath thereby making adjustments difficult. What isneeded is a system that retains the stent on the catheter even when amajority of the stent has been exposed by retraction of the sheath. Whatis also needed is a system that allows a stent to be re-sheathed evenafter a majority of the stent has been exposed by retraction of thesheath.

SUMMARY OF THE INVENTION

[0013] One embodiment of the present invention relates to an implantdelivery system that provides enhanced placement control of the implant.

[0014] A variety of advantages of the invention will be set forth inpart in the description that follows, and in part will be apparent fromthe description, or may be learned by practicing the invention. It is tobe understood that both the foregoing general description and thefollowing detailed description are exemplary and explanatory only andare not restrictive of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

[0015]FIG. 1 is a side elevation view of a stent delivery systemaccording to the present invention;

[0016]FIG. 2A is an enlarged cross-sectional view of detail A of FIG. 1with the stent in a compressed orientation;

[0017]FIG. 2B is an enlarged cross-sectional view of detail A of FIG. 1with the stent in a deployed (i.e., expanded) orientation;

[0018]FIG. 3 is an enlarged cross-sectional view of detail B of FIG. 1;

[0019]FIG. 4 is an enlarged cross-sectional view of detail C;

[0020]FIG. 5 is a cross-sectional view of the inner and outer tubularmembers of the stent delivery system of FIG. 1 taken along section line5-5 of FIG. 3;

[0021]FIG. 6A is a plan view of a first stent having an interlockstructure that interlocks with an interlock structure of a matingcollar, the stent and the collar are shown cut longitudinally and laidflat with an axial separation between the stent proximal end and themating collar;

[0022]FIG. 6B is the view of FIG. 6A with the stent proximal end andmating collar shown interlocked;

[0023]FIG. 6C is an end view of the stent of FIGS. 6A and 6B in itstubular configuration;

[0024]FIG. 7 is a laid flat, plan view of a second stent having aninterlock structure that interlocks with an interlock structure of amating collar, the collar includes rotational positioning indicators;

[0025]FIG. 8 is a laid flat, plan view of a third stent having aninterlock structure that interlocks with an interlock structure of amating collar, the collar includes rotational positioning notches;

[0026]FIG. 9 is a laid flat, plan view of a fourth stent having aninterlock structure that interlocks with an interlock structure of amating collar, the stent and the collar include a rotational alignmentkey and keyway;

[0027]FIG. 10 is a laid flat, plan view of a fifth stent having aninterlock structure that interlocks with an interlock structure of amating collar;

[0028]FIG. 11 is a laid flat, plan view of a sixth stent having aninterlock structure that interlocks with an interlock structure of amating collar;

[0029]FIG. 12 is a laid flat, plan view of a seventh stent having aninterlock structure that interlocks with rectangular posts formed on aninner body of a catheter;

[0030]FIG. 13 is a laid flat, plan view of a eighth stent having aninterlock structure that interlocks with an interlock structure of amating collar;

[0031]FIG. 14A is a laid flat, plan view of a ninth stent having aninterlock structure that interlocks with outwardly projecting line-likeprojections formed on the inner body of a catheter;

[0032]FIG. 14B shows the stent of FIG. 14A interlocked with theline-like projections;

[0033]FIG. 15A is a laid flat, plan view of a tenth stent having aninterlock structure that interlocks with outwardly projecting postsformed on the inner body of a catheter;

[0034]FIG. 15B shows the stent of FIG. 15A interlocked with the posts;and

[0035]FIGS. 16A and 16B show another delivery system that is anembodiment of the present invention.

DETAILED DESCRIPTION

[0036] With reference now to the various drawing figures in whichidentical elements are numbered identically throughout, a description ofa preferred embodiment of the present invention will now be provided.

[0037] With initial references to FIGS. 1-4, a stent delivery system 10is shown. The stent delivery system 10 is for delivery of a stent 12 toa deployment site in a body lumen of a patient's body. By way ofnon-limiting, representative example, the stent 12 may be aself-expanding stent having a construction such as that shown in U.S.Pat. No. 6,132,461. In one non-limiting embodiment, the stent can bemade of a superelastic metal such as nitinol, or the like. The stent 12may also be a coil stent or any other self-expanding stent. The stent 12includes a proximal end 12 a and a distal end 12 b. Anotherrepresentative stent is shown in U.S. patent application Ser. No.09/765,725, filed Jan. 18, 2001 and entitled STENT, which is herebyincorporated by reference.

[0038] The stent 12 is carried on the stent delivery system 10 in acollapsed (or reduced diameter) state as shown in FIG. 2A. Upon releaseof the stent 12 from the stent delivery system 10 (as will bedescribed), the stent 12 expands to an enlarged diameter (see FIG. 2B)to abut against the walls of the patient's lumen in order to supportpatency of the lumen.

[0039] The stent delivery system 10 includes an inner tubular member 14(i.e., also referred to as an elongated member) and an outer tubularmember 16. Both of the inner and outer tubular members 14 and 16 extendfrom proximal ends 14 a, 16 a to distal ends 14 b, 16 b.

[0040] The outer tubular member 16 is sized to be axially advancedthrough the patient's body lumen. The tubular member 16 is preferablysufficiently long for the distal end 16 b to be placed near thedeployment site in the patient's body lumen with the proximal end 16 aremaining external to the patient's body for manipulation by anoperator. By way of example, the outer tubular member 16 (also referredto as a sheath) may be a braid-reinforced polyester of tubularconstruction to resist kinking and to transmit axial forces along thelength of the sheath 16. The outer tubular member 16 may be of widelyvarying construction to permit varying degrees of flexibility of theouter tubular member 16 along its length.

[0041] As shown in FIG. 3, the proximal end 16 a of the outer tubularmember 16 is bonded to a manifold housing 20. The manifold housing 20 isthreadedly connected to a lock housing 22. A strain relief jacket 24 isconnected to the manifold housing 20 and surrounds the outer tubularmember 16 to provide strain relief for the outer tubular member 16.

[0042] The inner tubular member 14 is preferably formed of nylon but maybe constructed of any suitable material. As shown in FIG. 2B, the innertubular member 14 defines a stent attachment location 26 (i.e., a stentmounting location). The inner tubular member 14 also includes markers27, 28 that are attached to an outer surface of the inner tubular member14 (e.g., by techniques such as adhesive, heat fusion, interference fit,fasteners, intermediate members or other techniques). The attachmentlocation 26 is positioned between the markers 27, 28. The radiopaquemarkers 27, 28 permit a physician to accurately determine the positionof the stent attachment location 26 within the patient's lumen underfluoroscopic visualization. As will be described later in thespecification, in some embodiments, at least one of the markers 27, 28forms a collar including a geometry that interlocks with the stent 12 toprevent axial movement of the stent 12 relative to the inner tubularmember during transport and deployment of the stent 12. Materials formaking the radiopaque marker should have a density suitable forvisualization through fluoroscopic techniques. Exemplary materialscomprise tanalum, platinum, gold, tungsten and alloys of such metals. Insome embodiments, the markers can be coated with a radiopaque materialor filled with a radiopaque filler.

[0043] A tapered and flexible distal tip member 30 is secured to thedistal end 14 b of the inner tubular member 14. The highly flexibledistal tip member 30 permits advancement of the stent deployment system10 through the patient's lumen and minimizes trauma to the walls of thepatient's lumen. As shown in FIG. 2B, the inner tubular member 14preferably extends completely through the stent 12 when the stent 12 ismounted at the attachment location 26.

[0044] As best shown in FIGS. 3 and 4, the inner tube 14 passes throughboth the manifold housing 20 and lock housing 22. A stainless steeljacket 32 surrounds and is bonded to the inner tubular member 14.

[0045] At the inner tube proximal end 14 a, a port housing 34 is bondedto the stainless steel jacket 32. The port housing 34 has a tapered bore36 aligned with an inner lumen 38 of the tubular member 14. The innerlumen 38 extends completely through the inner tubular member 14 so thatthe entire delivery system 10 can be passed over a guide wire (notshown) initially positioned within the patient's lumen. Opposingsurfaces of the inner and outer tubular members 14 and 16, define afirst lumen 40 (best seen in FIG. 5). As described in U.S. patentapplication Ser. No. 09/765,719 filed on Jan. 18, 2001 and entitledSTENT DELIVERY SYSTEM WITH SPACER MEMBER, which is hereby incorporatedby reference, splines 18 can be provided between the inner and outertubular members 14 and 16.

[0046] As shown in FIG. 3, the manifold housing 20 carries an admissionport 42 for injecting a contrast media into the interior of the manifoldhousing 20. The interior of the manifold housing 20 is in fluid flowcommunication with the first lumen 40. Discharge ports 41 (shown inFIGS. 2A and 2B) are formed through the outer tubular member 16 topermit contrast media to flow from the first lumen 40 into the patient'sbody lumen.

[0047] As shown in FIG. 3, an O-ring 44 surrounds the stainless steeljacket 32 between the manifold housing 20 and lock housing 22. Uponthreaded connection of the manifold housing 20 to the lock housing 22,the O-ring 44 compresses against the stainless steel jacket 32 insealing engagement to prevent contrast media from flowing in any pathother than through the first lumen 40.

[0048] As shown in FIGS. 1 and 3, the lock housing 22 carries a threadedlocking member (or lock nut) 46 which can be turned to abut thestainless steel jacket 32. The lock nut 46 can be released to free thestainless steel jacket to move axially. According, when the lock nut 46engages the jacket 32, the jacket 32 (and attached inner tubular member14) cannot move relative to the lock housing 22, manifold housing 20 orthe outer tubular member 16. Upon release of the lock nut 46, the innertubular member 14 and outer tubular member 16 are free to slide axiallyrelative to one another between a transport position and a deployposition.

[0049] First and second handles 48, 50 are secured to the lock housing22 and jacket 32, respectively. In the transport position (shown in FIG.2A), the handles 48, 50 are spaced apart and the distal end of the outertubular member 16 forms a sheath that covers the stent attachmentlocation 26 to prevent premature deployment of the stent 12. When thehandle 48 is pulled rearwardly toward the handle 50, the outer tubularmember 16 slides rearwardly or proximally relative to the inner tubularmember 14. Preferably, the outer tubular member 16 slides rearwardly adistance sufficient to fully expose the stent attachment location 26 andpermit the stent 12 to freely expand toward its fully expanded diameter(see FIG. 2B). After such expansion, the stent delivery system can beproximally withdrawn through the expanded stent and removed.

[0050] As shown in FIG. 3, the first handle 48 is rotatably mounted on aflange 22 a of the lock housing 22. The first handle 48 surrounds thestainless steel jacket 32 and is freely rotatable about the longitudinalaxis of the jacket 32 and freely rotatable about the flange 22 a. Thefirst handle 48 is axially affixed to the lock housing 22 such thataxial forces applied to the first handle 48 are transmitted through thelock housing 22 and manifold housing 20 to the outer tubular member 16to axially move the outer tubular 16. However, rotary action of thefirst handle 48 about the axis of the stainless steel jacket 32 is nottransmitted to the housings 20, 22 or to the outer tubular member 16 byreason of the free rotation of the first handle 48 on flange 22 a.

[0051] As shown in FIG. 4, the second handle 50 is mounted on an anchor52 that is bonded to the stainless steel jacket 32 through any suitablemeans (such as by use of adhesives). The anchor 52 includes a flange 52a that is radial to the axis of the stainless steel jacket 32. Thesecond handle 50 is mounted on the flange 52 a and is free to rotate onthe anchor 52 about the axis of the stainless steel jacket 32. However,axial forces applied to the handle 50 are transmitted to the stainlesssteel jacket 32 which, being bonded to the inner tubular member 14,results in axial movement of the inner tubular member 14.

[0052] With the handle construction described above, relative axialmovement between the handles 48, 50 results in relative axial movementbetween the inner and outer tubular members 14, 16. Rotational movementof either of the handles 48, 50 does not affect rotational positioningof the inner or outer tubular members 14, 16 and does not affect axialpositioning of the inner and outer tubes 14, 16.

[0053] The free rotation of the handles 48, 50 results in ease of usefor a physician who may position his or her hands as desired withoutfear of interfering with any axial positioning of the inner and outertubular members 14, 16. The spacing between the handles 48, 50 is equalto the stroke between the transport position and the deploy position ofthe tubular members 14, 16. As a result, the spacing permits theoperator to have ready visual indication of the relative axialpositioning between the inner and outer tubular members 14, 16. Thisrelative axial positioning can be fixed by engaging the lock nut 46. Inany such positioning, contrast media can be injected through theadmission port 42 into the chamber 40 with the contrast media flowingout of the side ports 41 into the body lumen to permit visualizationunder fluoroscopy.

[0054] With stent deployment systems having premounted stents of variousaxial lengths, the positioning of the second handle 50 on the stainlesssteel jacket 32 can be selected at time of assembly so that a spacing S(see FIG. 1) between the handles 48, 50 corresponds to the length of thestent 12 carried on the stent deployment system. For example, in apreferred embodiment, the spacing S is about 10 millimeters longer thanthe deployed length of the stent. Accordingly, the user will know thatthe outer tubular member 16 has been fully retracted when the handles48, 50 have been pushed completely together to completely release thestent 12. Also, the freely rotatable handles 48, 50 are easy to holdfrom any angle without slippage. The lock nut 46 ensures that the stent12 will not deploy prematurely.

[0055] A concern with existing delivery systems for self-expandingstents is control of stent delivery. For example, due to their elasticcharacteristics, self-expanding stents have a tendency to propelthemselves axially outwardly from their restraining sheaths before thesheaths have been completely retracted. When this occurs, control ofstent placement is compromised since the stent may overshoot the desireddeployment site. Further, once the stent has been completely deployed,subsequent adjustment of the stent deployment location can be difficultbecause re-sheathing typically cannot be readily accomplished.

[0056] To address the above concerns, the delivery system 10 ispreferably equipped with an interlock configuration that constrainsrelative axial movement between the stent 12 and the inner tube 14 untilafter the sheath 16 has been fully retracted. For example, when thestent 12 is mounted on the inner tube 14 and restrained in thecompressed orientation by the sheath 16 as shown in FIG. 2A, a firstinterlock geometry (e.g., male interlock structures 82 as shown in FIG.2A) located at the proximal end of the stent 12 interlocks with a secondinterlock geometry (e.g., female interlock structures 84 as shown inFIG. 2A) defined by the proximal marker 27 (also referred to as acollar). The interlock geometries remain interlocked to constrain axialmovement of the stent 12 until after the sheath has been retractedbeyond a predetermined location (e.g., the proximal-most end 12 a of thestent 12). When the sheath 12 has been retracted beyond thepredetermined location, the interlock geometry of the stent 12 isallowed to expand. As the interlock geometry of the stent expands, theinterlock geometry of the stent disengages from the interlock geometryof the marker 27 thereby allowing the inner tube 14 of the catheter tobe moved axially relative to the stent without interference from theinterlock geometries.

[0057]FIGS. 6A and 6B illustrate the proximal end 12 a of the stent 12in relation to the marker 27 located at the proximal end of theattachment location 26. In FIGS. 6A and 6B, the stent 12 and the marker27 have been cut longitudinally and laid flat. The stent 12 has a lengthL and a circumference C. In FIG. 6A, the marker 27 and the stent 12 areshown disengaged from one another. In FIG. 6B marker 27 and the stent 12are shown interlocked. In both FIGS. 6A and 6B, the stent is in thereduced diameter configuration. Similarly, the stents depicted in FIGS.7-15B are shown in the reduced diameter orientation.

[0058] Referring to FIG. 6A, the stent 12 includes a plurality of struts86 (i.e., reinforcing members). At least some of the struts 86 have freeterminal ends that define the proximal and distal ends 12 a and 12 b ofthe stent 12. Male interlock structures 82 (i.e., keys) are provided atthe free terminal ends of the struts 86. As shown in FIG. 6A, the maleinterlock structures 82 include enlargements in the form of circularprojections. The circular projections include interlock portions 88 thatproject outwardly from the struts 86 in a circumferential direction(i.e., in a direction coinciding with the circumference C of the stent12). The interlock portions 88 include interlock surfaces 90 that facein an axial direction. The phrase “face in an axial direction” will beunderstood to mean that least a vector component of the surface 90 isperpendicular with respect to a longitudinal axis AA of the stent 12.Thus, the surface 90 need not be completely perpendicular relative tothe longitudinal axis of the stent 12 to be construed as facing in anaxial direction. In other words, a surface aligned at oblique anglerelative to the longitudinal axis of the stent 12 shall also beconstrued as facing in an axial direction since such surface has avector component that is perpendicular relative to the longitudinal axisof the stent.

[0059] As best shown schematically in FIG. 6C, the male interlockstructures 82 are preferably positioned within a region defined betweenan inner diameter D1 and an outer diameter D2 of the stent 12. This ispreferably true regardless of whether the stent 12 is in the expandeddiameter orientation or the reduced diameter orientation. Preferably, atleast portions of the interlock surfaces 90 are located within 5millimeters of the proximal end 12 a of the stent 12. More preferably,at least portions of the interlock surfaces 90 are located within 3millimeters of the proximal end 12 a of the stent 12. Most preferably,at least portions of the interlock surfaces 90 are located within 2millimeters of the proximal end 12 a of the stent 12.

[0060] Referring to FIG. 6A, the stent 12 includes a lumen reinforcingstructure including a plurality of struts 13 adapted to define opencells 15 (best shown in FIG. 2B) when the stent 12 is deployed.Preferably, the male interlock structures 82 are located within 5millimeter of the struts 13 that define the open cells 15. Morepreferably, the male interlock structures 82 are located within 4, 3 or2 millimeters of the struts 13 that define the open cells 15. Mostpreferably, the male interlock structures 82 are located within 1millimeter of the struts 13 that define the open cells 15. Because themale interlock structures 82 are located relatively close to thestructure defining the open cells 15, during deployment of the stent 12,the male interlock structures 82 will expand radially outwardlysimultaneously with the radial expansion of at least a portion of thecell defining structure. When the stent 12 is expanded, the interlockstructures 82 are preferably maintained generally within a boundarydefined by the inner and outer diameters of the cell defining portion ofthe stent, and preferably the interlock structures 82 are not biased orangled radially outwardly relative to the cell defining portion.

[0061] Still referring to FIGS. 6A and 6B, the marker 27 has an axialdistal edge 29 facing the proximal end 12 a of stent 12. Femaleinterlock structures 84 (i.e., sockets, openings, keyways, etc.) aredefined by the marker 27 adjacent the edge 29. The female interlockstructures 84 are configured to have a complimentary mating geometrywith respect to the male interlock structures 82 of the stent 12. Forexample, similar to the male interlock structures 82, the femaleinterlock structures 84 are shown having generally rounded or circularshapes. Each of the female interlock structures 84 includes interlocksurfaces 92 that face in an axial direction.

[0062] The geometry of the female interlock structures 84 is selected tomate with the predetermined geometry of the stent proximal end 12 a suchthat the stent 12 and the marker 27 can be axially coupled orinterlocked when the stent 12 is compressed at the mounting location 26.When the male and female interlock structures 82 and 84 are interlocked,the interlock surfaces 90 and 92 oppose and circumferentially overlapone another (see FIG. 6B) such that the stent is restricted from distalmovement relative to the marker 27.

[0063] With the specific embodiment shown, the stent 12 and collar 27are rotary coupled such that the stent 12 and collar 27 are restrictedfrom relative rotary motion (i.e., about axis X-X) when the stent 12 isin the collapsed state. The predetermined stent geometry of theinterlock structures 82 and the complementary mating geometry of thecollar 27 do not restrict relative radial motion. Namely, as theself-expanding stent 12 expands radially, the male interlock structures82 are free to radially move out of the female interlock structures 84.After such motion, the stent 12 is no longer coupled to the collar 27and the stent 12 and collar 27 are free to move axially, radially ortransversely to one another.

[0064] With the embodiment thus described, the mating features of thestent 12 and collar 27 prevent premature discharge of the stent 12 froma stent attachment location 26. As the outer sheath 16 is retracted, thesheath distal end 16 b exposes the distal end 12 b of the stent 12. Atthis point, the exposed distal end 12 b of the stent 12 is free forlimited expansion restrained by the remainder of the stent 12 beingcovered by the sheath 16 and by the attachment of the stent proximal end12 a to the proximal marker 27.

[0065] Further retraction of the sheath 16, permits still furtherexpansion of the stent 12. As the sheath distal end 12 b approaches thestent proximal end 12 a, the expansion of the stent material tends tourge the stent 12 to squeeze out of the small portion of the sheath 16now covering the stent 12. However, this propensity is overcome by theattachment of the stent proximal end 12 a to the collar 27 since anysuch ejection of the stent 12 would require axial separation of thestent 12 and collar 27. Such movement is prevented by the male interlockstructures 82 and the female interlock structures 84.

[0066] Therefore, as long any portion of the sheath 16 overlies the maleand female interlock structures 82 and 84, the proximal end 12 a of thestent 12 cannot expand and cannot axially move away from the collar 27.Accordingly, the stent 12 is not released from the attachment location26 until the physician has fully retracted the sheath 16 with the sheathdistal end 16 b retracted proximal to the proximal end of stentattachment location 26. The sheath distal end 16 b is provided with amarker 16 b′ (shown in FIGS. 2A and 2B) to permit visualization of therelative position of the sheath distal end 12 b and the markers 27, 28of the stent attachment location 26.

[0067] With the structure and operation thus described, the physicianhas greater control of the release of the stent 12. More accurate stentpositioning is attained. As long as even a small portion of the sheath16 is not fully retracted (e.g., at least 1 mm extends distally to theproximal end 12 a of the stent 12) the axial position of the stent 12can be adjusted by advancing or retracting the inner tubular member 14.Also, as long as a small portion of the sheath 16 remains covered by thesheath 16 (e.g., at least 1 mm), the stent 12 can be readily re-sheathedby moving the sheath 16 in a distal direction.

[0068] In the embodiment of FIGS. 6A and 6B, the female and maleinterlock structures 82 and 84 have complementary mating geometries. Itwill be appreciated that in alternative embodiments, the female and maleinterlock structures need not have complementary/identical shapes.Instead, to provide an interlock, it is only necessary for a portion ofthe male interlock to be received in the female interlock such thatmechanical interference or overlap between the interlocks prevents theinterlocks from being axially separated. This can be accomplishedwithout having identical mating shapes.

[0069] As described above, the interlock structure 84 of the inner tube14 is provided on the proximal marker 27. It will be appreciated thatthe interlock structure 84 need not be the same element as the markerbut could be a separate part. As a separate part, the interlockstructure could be integrally formed/connected with the exterior of theinner tube 14, connected to the outer surface of the inner tube byconventional techniques (e.g., adhesive, fasteners, fusion bonding,etc.), or be connected to the outer surface of the inner tube 14 by oneor more intermediate members. Further, the embodiment of FIGS. 6A and 6Bshows that the interlock between the stent 12 and the tube 14 isprovided at the proximal end 12 a of the stent 12 b. It will beappreciated that for certain embodiments, the interlock between theinner tube 14 and the stent 12 can be provided at the distal end 12 b ofthe stent 12 (e.g., for a distally retractable sheath). Moreover, whilethe embodiment of FIGS. 6A and 6B shows interlock structures provided atall of the proximal ends of the struts 86, the invention is not solimited. For example, in some embodiments, only some of the struts 86may include interlock structures. While in certain embodiments it may bedesirable to use only one interlock structure at the end of the stent12, it is preferable to use at least two separate/discrete interlockstructures uniformly spaced about the circumference of the stent. It ismore preferable to use at least 4 separate/discrete interlock structuresthat are preferably uniformly spaced about the circumference of thestent.

[0070] The collar 27 may be provided with indicia to indicate to aphysician the position of the collar 27 (and hence the stent 12) whenthe combination is in a patient's vessel and is being visualized underfluoroscopy. In the embodiment of FIGS. 6A and 6B, the indicia is shownas cutouts 15 in the collar 27. FIG. 7 shows a collar 27′ having indiciain the form of proximal projections 15′ off of the proximal edge of thecollar 27′. FIG. 8 shows a collar 27′ having indicia in the form oftriangular notches 15′ defined at the proximal edge of the collar 27′.In the embodiments shown, the indicia 15, 15′ and 15″ are spaced apartcircumferentially on their respective collars 27, 27′ and 27″ so thatthe indicia are 180 degrees apart.

[0071] In the embodiment of FIGS. 6A and 6B, the pattern and shape ofthe male interlock structures 82 and the female interlock structures 84are symmetrical about the stent axis X-X. As a result, the stent 12 canbe affixed to the collar 27 in any one of a plurality of rotaryalignments about axis X-X.

[0072]FIG. 9 illustrates an embodiment of a collar 127 and stent 112where the symmetrical pattern is interrupted. In the example of FIG. 9,a single unique key 117 is provided (which, in the example shown, has asquare geometry compared to the circular geometry of remaining maleinterlock structures 182). Similarly, the collar 127 has a unique keyway117 a to mate with the unique key 117. As a result, the stent 112 canonly be affixed to the collar 127 in one rotary alignment.

[0073] In all of the above embodiments, once the position of a stent isfixed to a collar, a non-symmetrical stent feature (e.g., an opening forplacement at a bifurcation in a vessel) can be aligned with the indicia(or, if desired, a single indicia can be provided on the collar).Therefore, a physician can easily visualize the position of anynon-symmetrical stent feature.

[0074]FIG. 10 illustrates an embodiment of a stent 212 and radiopaquecollar 227 having another interlock configuration. The collar 227 hascircumferential slots 228 for assisting in adhesively bonding the collar227 to the outer surface of the inner tube 14. The stent 212 hasproximal and distal ends 212 a and 212 b. The stent also includesproximal end struts 286 a having free ends at which male interlockstructures 282 are formed. The male interlock structures 282 are formedby notches cut into the proximal end struts 286 a. The male interlockstructures 282 include axially facing interlock surfaces 290 that facein a distal direction. Preferably, the surfaces 290 are located within 5millimeters of the proximal end 212 a of the stent 212, and within 1, 2,3, 4 or 5 millimeters of a cell defining portion of the stent.

[0075] The collar 227 includes female interlock structures 284 in theform of sockets. The sockets are partially defined by projectionsadapted to fit within the notches cut into the proximal end struts 286a. The projections define axially facing interlock surfaces 292 thatface in a proximal direction. When the male and female interlockstructures 282 and 284 are interlocked, the surfaces 290 and 292 opposeone another to prevent the male interlock structures 282 from beingaxially withdrawn from the female interlock structures 284.

[0076]FIG. 11 illustrates an embodiment of a stent 312 and radiopaquecollar 327 having another interlock configuration. The collar 327 hascircumferential slots 328 for assisting in adhesively bonding the collar327 to the outer surface of the inner tube 14. The stent 312 hasproximal and distal ends 312 a and 312 b. The stent also includesproximal end struts 386 a having free ends at which male interlockstructures 382 are formed. The male interlock structures 382 are formedby enlarged heads (i.e., protuberances or keys) located at the ends ofthe end struts 386 a. The male interlock structures 382 include axiallyfacing interlock surfaces 390 that face in a distal direction.Preferably, the surfaces 390 are located within 5 millimeters of theproximal end 312 a of the stent 312, and within 1, 2, 3, 4 or 5millimeters of a cell defining region of the stent. The collar 327includes female interlock structures 384 in the form of sockets. Thefemale interlock structures 384 include axially facing interlocksurfaces 392 that face in a proximal direction. When the male and femaleinterlock structures 382 and 384 are interlocked, the surfaces 390 and392 oppose one another to prevent the male interlock structures 382 frombeing axially withdrawn from the female interlock structures 384.

[0077]FIG. 12 illustrates an embodiment of a stent 412 including femaleinterlock structures 484. The female interlock structures 484 preferablyinclude distally facing interlock surfaces 492 located within 5 mm of aproximal end 412 a of the stent 412 and within 1, 2, 3, 4 or 5millimeters of a cell defining region of the stent. The female interlockstructures 484 are sized to receive male interlock structures 482 in theform of rectangular posts. Preferably, the posts are connected to theouter surface of the inner tube 14 (e.g., integrally or otherwise). Theposts define proximally facing interlock surfaces 490. When the femaleand male interlock structures 484 and 482 are coupled, the surfaces 490and 492 engage each other to prevent distal movement of the stent 412relative to the posts.

[0078]FIG. 13 illustrates an embodiment of a stent 512 including maleinterlock structures 582 in the form of hooks. The male interlockstructures 582 preferably include distally facing interlock surfaces 590located within 5 mm of a proximal end 512 a of the stent 512 and within1, 2, 3, 4 or 5 millimeters of a cell defining region of the stent. Themale interlock structures 582 are sized to fit within female interlockstructures 584 defined by a collar 527. The female interlock structures584 define proximally facing interlock surfaces 592. When the female andmale interlock structures 584 and 582 are coupled, the surfaces 590 and592 engage each other to prevent distal movement of the stent 512relative to the collar 527.

[0079]FIGS. 14A and 14B illustrate an embodiment of a stent 612including female interlock structures 684 in the form of longitudinalslots between or within struts. The female interlock structures 684preferably include distally facing interlock surfaces 692 (e.g., definedby the proximal ends of the slots) located within 5 mm of a proximal end612 a of the stent 612 and within 1, 2, 3, 4 or 5 millimeters of a celldefining region of the stent. The female interlock structures 684 aresized to receive male interlock structures 682 in the form of linearposts. Preferably, the posts are connected to the outer surface of theinner tube 14 (e.g., integrally or otherwise). The posts defineproximally facing interlock surfaces 690 (e.g., at the proximal ends ofthe posts). When the female and male interlock structures 684 and 682are coupled as shown in FIG. 14B, the surfaces 690 and 692 engage eachother to prevent distal movement of the stent 612 relative to the posts.

[0080]FIGS. 15A and 15B illustrate an embodiment of a stent 712including female interlock structures 784 in the form of circularopenings defined through enlarged strut ends of the stent 712. Thefemale interlock structures 784 preferably include distally facinginterlock surfaces 792 located within 5 mm of a proximal end 712 a ofthe stent 712 and within 1, 2, 3, 4 or 5 millimeters of a cell definingregion of the stent. The female interlock structures 784 are sized toreceive male interlock structures 782 in the form of cylindrical postsor pins. Preferably, the posts are connected to the outer surface of theinner tube 14 (e.g., integrally or otherwise). The posts defineproximally facing interlock surfaces 790. When the female and maleinterlock structures 784 and 782 are coupled as shown in FIG. 15B, thesurfaces 790 and 792 engage each other to prevent distal movement of thestent 712 relative to the posts.

[0081]FIGS. 16A and 16B show a stent delivery system 10′ that is anotherembodiment of the present invention. The delivery system 10′ includes aninner member 14′ and an outer sheath 16′. The inner member 14′ includesa flexible distal tip 30′ and a stent mounting location 26′. Proximaland distal markers 27′ and 28′ are located on opposite sides of themounting location 26′. The proximal marker 27′ includes interlockstructures in the form of receivers 84′ or receptacles. The receivers84′ are adapted to receive and interlock with interlock structures inthe form of enlargements 82′ provided at the proximal end of selfexpanding stent 12′. The enlargements 82′ are preferably within 1, 2, 3,4 or 5 millimeters of cell defining structures 83′ of the stent 12′.

[0082] While the various embodiments of the present invention haverelated to stents and stent delivery systems, the scope of the presentinvention is not so limited. For example, while particularly suited forstent delivery systems, it will be appreciated that the various aspectsof the present invention are also applicable to systems for deliveringother types of self-expandable implants. By way of non-limiting example,other types of self-expanding implants include anastomosis devices,blood filters, grafts, vena cava filters, percutaneous valves, or otherdevices. Also, while it is preferred for the interlocks of the presentinvention to be within 5 millimeters of an end of their correspondingimplant to enhance deployment control, larger spacings could be used forcertain applications. Similarly, while it is preferred for theinterlocks to be within 5, 4, 3, 2 or 1 millimeters of cell definingregions of the stents, other spacings could be used in certainalternative embodiments.

[0083] It has been shown how the objects of the invention have beenattained in a preferred manner. Modifications and equivalents of thedisclosed concepts are intended to be included within the scope of theclaims.

What is claimed is:
 1. An implant delivery system comprising: a catheterincluding an elongated member having an implant mounting location; anexpandable implant mounted on the elongated body at the implant mountinglocation, the implant being expandable from a compressed orientation toan expanded orientation, the implant including first and second ends; asheath mounted on the elongated member, the sheath being positionable ina transport position in which the sheath covers the implant mounted atthe implant mounting location, the sheath also being positionable in adeploy position in which the implant is exposed; the implant including afirst interlock structure and the elongated body including a secondinterlock structure, the first and second interlock structuresinterlocking to constrain axial movement of the implant relative to theelongated member when the implant is at least partially within thesheath, and the first and second interlock structures not constrainingradial expansion of the implant; one of the first and second interlockstructures including a male interlock structure and the other of thefirst and second interlock structures including a female interlockstructure adapted to receive the male interlock structure when theimplant is in the compressed orientation; the implant including a celldefining region; and at least a portion of the first interlock structurebeing positioned within 5 millimeters of the first end of the implantand within 5 millimeters of the cell defining region of the implant. 2.The implant delivery system of claim 1, wherein the implant comprises astent.
 3. The implant delivery system of claim 1, wherein at least aportion of the first interlock structure is positioned within 2millimeters of the first end of the implant.
 4. The implant deliverysystem of claim 1, wherein the elongated body includes a radiopaquemarker positioned adjacent to the implant mounting location, and whereinthe marker defines the second interlock structure.
 5. The implantdelivery system of claim 1, wherein the first end of the implant is aproximal end of the implant.
 6. The implant delivery system of claim 1,wherein the implant includes a plurality of separate first interlockstructures having at least portions positioned within 5 millimeters ofthe first end, and wherein the elongated body includes a plurality ofsecond interlock structures for interlocking with the first interlockstructures.
 7. The implant delivery system of claim 1, wherein the firstinterlock structure is the male interlock structure and the secondinterlock structure is the female interlock structure.
 8. The implantdelivery system of claim 7, wherein the male interlock structureincludes an enlargement positioned at the first end of the implant. 9.The implant delivery system of claim 8, wherein the implant includes aplurality of enlargements at the first end of the implant.
 10. Theimplant delivery system of claim 8, wherein the male interlock structureincludes a circumferential projection positioned at the first end of theimplant.
 11. The implant delivery system of claim 10, wherein theimplant includes a plurality of the circumferential projections at thefirst end of the implant.
 12. The implant delivery system of claim 1,wherein the first interlock structure is the female interlock structureand the second interlock structure is the male interlock structure. 13.The implant delivery system of claim 12, wherein the implant includesstruts, and the female interlock structure includes a post openingdefined through at least one of the struts.
 14. The implant deliverysystem of claim 13, wherein the implant includes a plurality of the postopenings.
 15. The implant delivery system of claim 13, wherein theimplant includes struts, and the female interlock structure includes anopening between the struts.
 16. The implant delivery system of claim 1,wherein the first interlock structure is within 2 millimeters of thecell defining region of the implant.
 17. The implant delivery system ofclaim 1, wherein the first interlock structure is within 1 millimeter ofthe cell defining region of the implant.
 18. The implant delivery systemof claim 1, wherein the elongated member extends completely through theimplant.
 19. The implant delivery system of claim 1, wherein the celldefining region of the implant includes a boundary defined by an innerdiameter and an outer diameter of the implant, and wherein the firstinterlock structure stays generally within the boundary after theimplant has been deployed.
 20. The implant delivery system of claim 1,wherein the first interlock structure is not radially outwardly biasedrelative to the cell defining region of the implant.
 21. An implantdelivery system comprising: a catheter including an elongated memberhaving an implant mounting location; an expandable implant mounted onthe elongated body at the implant mounting location, the implant beingexpandable from a compressed orientation to an expanded orientation, theimplant including first and second ends; a sheath mounted on theelongated member, the sheath being positionable in a transport positionin which the sheath covers the implant mounted at the implant mountinglocation, the sheath also being positionable in a deploy position inwhich the implant is exposed; the implant including a cell definingregion, the implant also including a plurality of struts at least someof which have terminal ends defining the first end of the implant, theimplant also including at least two enlargements positioned at theterminal ends of the struts, the enlargements being located within 5millimeters of the cell defining region of the implant; and theelongated body including receptacles that receive the enlargements toconstrain axial movement of the implant relative to the elongated memberwhen the implant is at least partially within the sheath.
 22. Theimplant delivery system of claim 21, wherein the elongated body includesa radiopaque marker positioned adjacent to the implant mountinglocation, and wherein the marker defines the receptacles.
 23. Theimplant delivery system of claim 21, wherein the first end of theimplant is a proximal end of the implant.
 24. The implant deliverysystem of claim 21, wherein the enlargements are within 2 millimeters ofthe cell defining region of the implant.
 25. The implant delivery systemof claim 21, wherein the enlargements are within 1 millimeter of thecell defining region of the implant.
 26. The implant delivery system ofclaim 21, wherein the elongated member extends completely through theimplant.
 27. The implant delivery system of claim 21, wherein the celldefining region of the implant includes a boundary defined by an innerdiameter and an outer diameter of the implant, and wherein theenlargements stay generally within the boundary after the implant hasbeen deployed.
 28. The implant delivery system of claim 21, wherein theenlargements are not radially outwardly biased relative to the celldefining region of the implant.
 29. An implant delivery systemcomprising: a catheter including an elongated member having an implantmounting location; an expandable implant mounted on the elongated bodyat the implant mounting location, the implant being expandable from acompressed orientation to an expanded orientation, the implant includingfirst and second ends; a sheath mounted on the elongated member, thesheath being positionable in a transport position in which the sheathcovers the implant mounted at the implant mounting location, the sheathalso being positionable in a deploy position in which the implant isexposed; the implant including a cell defining region and first andsecond ends, the implant also including at least two female maleinterlock structures positioned within 5 millimeters of the first end ofthe implant and within 5 millimeters of the cell defining region of theimplant; and the elongated body including male interlock structures thatare received within the female interlock structures to constrain axialmovement of the implant relative to the elongated member when theimplant is at least partially within the sheath, the male and femaleinterlock structures not constraining radial expansion of the implant.30. The implant delivery system of claim 29, wherein the elongated bodyincludes a radiopaque marker positioned adjacent to the implant mountinglocation, and wherein the marker includes the male interlock structures.31. The implant delivery system of claim 29, wherein the first end ofthe implant is a proximal end of the implant.
 32. The implant deliverysystem of claim 29, wherein the female interlock structures are within 2millimeters of the cell defining region of the implant.
 33. The implantdelivery system of claim 29, wherein the female interlock structures arewithin 1 millimeter of the cell defining region of the implant.
 34. Theimplant delivery system of claim 29, wherein the elongated memberextends completely through the implant.
 35. An implant delivery systemcomprising: a catheter including an elongated member having an implantmounting location; an expandable implant mounted on the elongated bodyat the implant mounting location, the implant being expandable from acompressed orientation to an expanded orientation, the implant includingfirst and second ends; a sheath mounted on the elongated member, thesheath being positionable in a transport position in which the sheathcovers the implant mounted at the implant mounting location, the sheathalso being positionable in a deploy position in which the implant isexposed; a marker attached to the elongated member, the marker includingstructure that interlocks with the implant to constrain axial movementof the implant relative to the elongated member when the implant is atleast partially within the sheath.
 36. An implant delivery systemcomprising: a catheter including an elongated member having an implantmounting location; an expandable implant mounted on the elongated bodyat the implant mounting location, the implant being expandable from acompressed orientation to an expanded orientation, the implant includingfirst and second ends; a sheath mounted on the elongated member, thesheath being positionable in a transport position in which the sheathcovers the implant mounted at the implant mounting location, the sheathalso being positionable in a deploy position in which the implant isexposed; the implant including a first interlock structure and theelongated body including a second interlock structure, the first andsecond interlock structures interlocking to constrain axial movement ofthe implant relative to the elongated member when the implant is atleast partially within the sheath, and the first and second interlockstructures not constraining radial expansion of the implant; one of thefirst and second interlock structures including a male interlockstructure and the other of the first and second interlock structuresincluding a female interlock structure adapted to receive the maleinterlock structure when the implant is in the compressed orientation;and at least a portion of the first interlock structure being positionedwithin 5 millimeters of the first end of the implant, and the elongatedmember extending through the implant at the implant mounting location.37. The implant delivery system of claim 36, wherein at least a portionof the first interlock structure is positioned within 2 millimeters ofthe first end of the implant.
 38. An implant delivery system comprising:a catheter including an elongated member having an implant mountinglocation; an expandable implant mounted on the elongated body at theimplant mounting location, the implant being expandable from acompressed orientation to an expanded orientation, the implant includingfirst and second ends; a sheath mounted on the elongated member, thesheath being positionable in a transport position in which the sheathcovers the implant mounted at the implant mounting location, the sheathalso being positionable in a deploy position in which the implant isexposed; the implant including a first interlock structure and theelongated body including a second interlock structure, the first andsecond interlock structures interlocking to constrain axial movement ofthe implant relative to the elongated member when the implant is atleast partially within the sheath, and the first and second interlockstructures not constraining radial expansion of the implant; one of thefirst and second interlock structures including a male interlockstructure and the other of the first and second interlock structuresincluding a female interlock structure adapted to receive the maleinterlock structure when the implant is in the compressed orientation;the implant including a cell defining region that includes a boundarydefined by an inner diameter and an outer diameter of the implant, thefirst interlock structure being configured to stay generally within theboundary after the implant has been deployed; and at least a portion ofthe first interlock structure being positioned within 5 millimeters ofthe first end of the implant.
 39. The implant delivery system of claim38, wherein at least a portion of the first interlock structure ispositioned within 2 millimeters of the first end of the implant.
 40. Amethod for deploying a self-expandable implant with a deployment system,the deployment system including a sheath for holding the implant in acompressed orientation, the implant including first and second ends, theimplant also including an interlock surface positioned between inner andouter diameters of the implant, the interlock surface being locatedwithin 5 millimeters of the first end of the implant, the methodcomprising: generating relative movement between the implant and thesheath to expose the implant; engaging the interlock surface with aretainer as the implant is exposed to prevent the implant fromprematurely exiting the sheath; and after the implant has been exposedbeyond the interlock surface, disengaging the interlock surface from theretainer by self-expanding the implant, wherein the interlock surfacedisengages from the retainer simultaneous with the expansion of a celldefining portion of the implant.
 41. The method of claim 40, wherein theimplant is a stent.
 42. The method of claim 40, wherein the interlocksurface is within 2 millimeters of the first end of the implant.
 43. Themethod of claim 40, wherein the first end of the implant is a proximalend of the implant and the second end of the implant is a distal end ofthe implant.